Direct thermal printing is a non-impact printing process where heat is applied to thermal paper to produce a visible color change. Prior to printing, the thermal paper is coated with a formulation comprising a low melting point solid, acid, and dye, the dye being one that changes color upon a change in pH. Heat is then applied by a printhead as the paper travels through a thermal printer. The application of heat melts the solid, allowing the dye and acid to react resulting in a color change. The printhead may be configured to heat certain areas of the thermal paper thereby activating some or all of the color chemistry such that words, images, or other indicia may be created.
Applicant has identified a number of deficiencies and problems associated with conventional thermal papers and thermal printing processes. Through applied effort, ingenuity, and innovation, many of these identified problems have been solved by developing solutions that are included in various embodiments of the present invention, which are described in detail below.